The aim of the study is to enhance the productivity of solar stills using an unsaturated porous medium (sand) initially saturated by salty water and using concentrating reflector. This paper concentrates on the mathematical model for the porous medium and its solution using a finite volume approach. Previous studies for solar still, using porous medium have been mainly concerned with design parameters to improve the solar still performance and its productivity. Some authors have interested in adding wick media in the basin of solar still without conditions applied this media. The researchers studied the heat and mass transfer from saturated wick media; they did not interest in the nature of wick and did not consider the thermophysical properties of porous medium. The previous studies deal with wick medium with high water content and liquid saturation in wick medium did not determine. Most of the authors did not give solute initial concentration and all did not give the concentration which has caused precipitated salt in the pores. The previous works did not consider salt crystallization in pores network. The enhanced still should be augmented by compound parabolic concentrator (CPC), and unsaturated porous medium. For partially saturated porous media liquid water rises through the porous medium by capillary action.